1.4 Segments, Rays, Parallel Lines and Planes

1. 1.4 Segments, Rays, Parallel Lines and Planes 1.4 Segments, Rays, Parallel Lines and Planes “I have always grown from my problems and challenges.” -Carol Burnett “I have always grown from my problems and challenges.” -Carol Burnett

2. Terms A segment is the part of a line consisting of two endpoints and the points between them. A ray is one endpoint and all of the points on one side of the endpoint. Opposite rays are two collinear rays with the same endpoint. Opposite rays always form a line. A B

3. Naming Name the segments and rays. Three segments: Four rays: C B B A

4. Parallel… ?? • Visualize a plane (it’s flat). • Think of two lines that are both in the plane. • Now make sure that the two lines do not intersect. [PARALLEL] • Notice that the lines are coplanar (in the same plane). • Now start over with a blank plane. • Think of one line in the plane. • Think of another line that can’t be included in the plane, even if you rotated the plane (remember: the plane has to be flat – it can’t turn a corner). • Now make sure that those two lines do not intersect. • This is different than parallel because the lines are noncoplanar (not in the same plane).

5. Terms Parallel lines are coplanar lines that do not intersect. Skew lines are noncoplanar; therefore, we can’t say they’re parallel, but we can say that they do not intersect. Do skew lines “look” parallel?

7. Terms Parallel planes are planes that do not intersect. *Note: A line and a plane that do not intersect with each other are also parallel. Example: 1. Identify two parallel planes. 2. Identify a plane and a line that are parallel. G H A C J I D B

8. 1.4 Segments, Rays, Parallel Lines and Planes HW: 4-15, 16-22 EVEN, Page 30 #1-19 ODD (linear equations review) Terms: segment, ray, opposite rays, parallel lines, skew lines, parallel planes “I have always grown from my problems and challenges.” -Carol Burnett